Development of sensory properties via barrel aging is one of the most demanding artistic activities of winemaking.

Sensory ‘pigment’ is drawn fromthe vineyard and the brush is a stainless steel tank or oak barrel.

By Gary Strachan I

have often written that there are only two processes in winemaking: Flavours are created in the vineyard and extracted during winemaking. I should probably add a third: Flavours are modified by fining. Apart from the removal of gas bubbles from molten glass, no one but a wine or beer maker seems to use the term fining. If I were a visual artist, I would compare fining to the touches given to a painting to emphasize or suppress an image; the strength of highlights or depth of shadows. A winemaker is a sensory artist. His pigment is a drawn from the vineyard and his brush a stainless steel tank or oak barrel.

There are no two identical wines. Each wine is unique if you search out the details. The winemaker’s mental image shapes the sensory properties, and lab analyses give reassurance of the pathway to create the wine conceived in the mind.

The fundamental structure of a wine is determined by the chosen variety, the climate and soil in which it is

grown, vineyard management, and stage of maturity at which it is harvested. The winemaker must then decide on the strategy to be used to extract flavours.

There are so many ways to extract a grape that this stage alone is sufficient to account for the variation between wines of the same variety from different wineries.

This is not to minimize the influence of other factors, but winemakers often develop an extraction style using favoured techniques. Those who become familiar with a particular winemaker’s style can often recognize wines from that winery, even though they may be from a different grape variety. No other memory is as persistent as that of smell. In a perfect world, there would be little else required of the winemaker except to extract, ferment, stabilize the wine, and clarify it for bottling. But nothing is that perfect. Sometimes a wine doesn’t settle easily or there may be an off-note on the palate. Now is the time for a fining agent.

The most fundamental fining agents are those which are insoluble, but have a property which enables them to remove an undesired component from a wine. The best known of these is bentonite clay, which is used to remove undesired protein from white wines.

Soluble protein can return to undermine the winemaker’s vision of a near-perfect white wine by creating a haze months or years after it has been bottled.

A grape-derived alternative to bentonite is tannin. Most red wines have enough tannin that they require no bentonite.

Tannin and bentonite each have an opposite molecular charge to protein, thus soluble protein will be neutralized by tannin or bentonite and will precipitate. Higher levels of tannin remain in the wine and contribute to mouth feel and astringency, but excess bentonite can be a serious problem because it can create a non filterable haze.

During the past few years we have learned a great deal about many traditional practices of winemaking and have put a new spin on them. Winemakers have used a process called bâttonage for centuries, but in recent years an objective examination of the process revealed unrecognized benefits associated with the practice. In addition to imparting savoury sensory notes, the practice increases body and imparts antioxidant properties to the wine. It consists of allowing the wine to remain in contact with the lees for an extended time. The lees are regularly stirred in order to resuspend them in the wine and assist the dead yeast cells to break down and release their contents. In recent years, wine ingredient suppliers have recognized the risk of developing off flavours that

accompanies bâttonage and have made autolyzed yeast available as a wine treatment. It’s become a simpler, more consistent part of the winemaker’s palette (not to be confused with palate,